摘要: |
One of the most important and difficult decisions faced by transportation officials on a regular basis is how to best allocate limited resources towards repair and maintenance of transportation infrastructure. To aid in the decision making process, efficient and reliable condition assessment tools are needed so that structurally deficient bridges, pavements and foundations can be identified and ranked in terms of their health. Such information enables decision makers to distribute resources towards those assets in greatest need of repair or retrofit. The goal of the proposed research is to investigate a promising innovation in the impact-echo (IE) nondestructive evaluation (NDE) method, whereby traditional ground-coupled transducers are replaced with air-coupled transducers. The accuracy of the method in detecting the location and extent of various defects in reinforced concrete bridge decks such as delaminations, voids, and cracking will be determined in the laboratory using a test slab. To provide improvements in the quality of the data, signal processing techniques and an active noise-cancelling technique will be examined. The air-coupled impact-echo approach will then be performed on a bridge deck and compared to results of other NDE methods as part of an existing pooled-fund structural health monitoring (SHM) study. Pending successful performance of the air-coupled impact-echo method, preliminary design recommendations for a mobile scanning system will also be developed in the proposed study. The advantage of an air-coupled IE method is that testing time would be greatly reduced by eliminating the requirement to physically couple transducers to the structure at each measurement point. The method could therefore be implemented in a mobile scanning system for accelerated 2D profiling of bridge decks and pavements, enabling the structural health of transportation infrastructure to be assessed and monitored with greater efficiency. A mobile scanning system may also eliminate the need for lane-closures and traffic direction crews. |